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  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK  ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
  • C09C1/00—Treatment of specific inorganic materials other than fibrous fillers; Preparation of carbon black
  • C09C1/36—Compounds of titanium
  • C09C1/3692—Combinations of treatments provided for in groups C09C1/3615 - C09C1/3684
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
  • C01G23/00—Compounds of titanium
  • C01G23/04—Oxides; Hydroxides
  • C01G23/047—Titanium dioxide
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D17/00—Pigment pastes, e.g. for mixing in paints
  • C09D17/004—Pigment pastes, e.g. for mixing in paints containing an inorganic pigment
  • C09D17/007—Metal oxide
  • C09D17/008—Titanium dioxide
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
  • C01G23/00—Compounds of titanium
  • C01G23/04—Oxides; Hydroxides
  • C01G23/047—Titanium dioxide
  • C01G23/08—Drying; Calcining ; After treatment of titanium oxide
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  • C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK  ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
  • C09C1/00—Treatment of specific inorganic materials other than fibrous fillers; Preparation of carbon black
  • C09C1/36—Compounds of titanium
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  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK  ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
  • C09C1/00—Treatment of specific inorganic materials other than fibrous fillers; Preparation of carbon black
  • C09C1/36—Compounds of titanium
  • C09C1/3607—Titanium dioxide
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK  ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
  • C09C3/00—Treatment in general of inorganic materials, other than fibrous fillers, to enhance their pigmenting or filling properties
  • C09C3/08—Treatment with low-molecular-weight non-polymer organic compounds
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  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK  ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
  • C09C3/00—Treatment in general of inorganic materials, other than fibrous fillers, to enhance their pigmenting or filling properties
  • C09C3/12—Treatment with organosilicon compounds
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D17/00—Pigment pastes, e.g. for mixing in paints

Definitions

• the present invention relates to an organic solvent dispersion of titanium oxide particles and a method for producing the same.
• titanium oxide particles have excellent stability and transparency, and preferably have a low viscosity while containing titanium oxide particles at a high content.
• the present invention relates to a method for producing an organic solvent dispersion of particles.
• organic solvent dispersion of titanium oxide particles obtained by the present invention has the characteristics as described above, for example, various applications in the optical field, in particular, optical composite resins such as LED sealing resins and antireflection films. It is useful as a material.
• inorganic oxide particle dispersions such as silica, alumina, zinc oxide, tin oxide, zirconia, and titania have been used in various industrial fields, particularly in the optical field, to adjust the refractive index. ing.
• titania has a high refractive index and is preferably used to increase the refractive index of optical materials.
• Inorganic oxide particles including titanium oxide particles, generally have good dispersibility in aqueous solvents, but generally have low dispersibility in organic solvents.
• an organic solvent dispersion of titanium oxide In the production of an organic solvent dispersion of titanium oxide, a method using a silane coupling agent has been proposed.
• the titanium oxide fine particle alcohol dispersion is mixed with a silane coupling agent in the presence of acetic acid and stirred to surface-treat the titanium oxide fine particles, and then the titanium oxide fine particle alcohol dispersion is a dispersion medium.
• a method has been proposed in which the alcohol is replaced with a lipophilic organic solvent such as methyl ethyl ketone, thus obtaining a lipophilic organic solvent dispersion of titanium oxide fine particles (see Patent Document 3).
• the obtained organic solvent dispersion may not be sufficiently satisfactory in transparency depending on the use, and the viscosity increases with time.
• organic solvent dispersions of titanium oxide particles that are excellent in stability and transparency.
• the present invention has been made in order to solve the above-described problems in the organic solvent dispersion of titanium oxide particles, and is excellent in stability and transparency, and preferably contains titanium oxide particles at a high content. However, it aims at providing the manufacturing method of the organic-solvent dispersion of the titanium oxide particle which has low viscosity.
• a method for producing an organic solvent dispersion of titanium oxide particles obtained by dispersing titanium oxide particles in an organic solvent excluding methanol and ethanol (A) Treatment of an alcohol dispersion of titanium oxide particles obtained by dispersing titanium oxide particles in at least one alcohol solvent selected from methanol and ethanol with a surface treatment agent containing a silane coupling agent and 12-hydroxystearic acid And a surface treatment step for surface-treating the titanium oxide particles, (B) a solvent replacement step of replacing the alcohol solvent, which is a dispersion medium in the alcohol dispersion of the surface-treated titanium oxide particles, with an organic solvent other than the alcohol solvent;
• the silane coupling agent is represented by the general formula (I) (RO) n- Si-X 4-n (I) (In the formula, R represents an alkyl group having 1 to 4 carbon atoms, n represents 2 or 3, and X represents an alkyl group, a fluorinated alkyl group, a vinyl group, or a (meth)
• an organic solvent dispersion in which titanium oxide particles are preferably dispersed in the organic solvent at a content of 10% by weight or more.
• the titanium oxide particles are surface-treated using 1 to 40 parts by weight of the silane coupling agent and 1 to 80 parts by weight of 12-hydroxystearic acid with respect to 100 parts by weight of the titanium oxide particles.
• the alcohol dispersion of titanium oxide particles contains 10% by weight or more of titanium oxide particles, D50 is in the range of 1 to 20 nm, and transmittance at a wavelength of 500 nm is 40% or more.
• the transmittance at a wavelength of 800 nm is preferably 80% or more.
• an alcohol dispersion of the titanium oxide particles used in the surface treatment step is converted into the following steps (a) to (c): (A) a step of wet dispersion treatment of an aqueous slurry of titanium oxide particles in the presence of acetic acid and nitric acid with a medium stirring mill or a high-pressure disperser to obtain an aqueous dispersion of titanium oxide particles; (B) a step of washing the aqueous dispersion of titanium oxide particles obtained in the step (a), (C) a step of replacing water, which is a dispersion medium of the aqueous dispersion of titanium oxide particles obtained in the step (b), with at least one alcohol solvent selected from methanol and ethanol; It is preferable that it was obtained by the method containing.
• a surface treatment agent comprising a titanium oxide particle alcohol dispersion obtained by dispersing titanium oxide particles in at least one alcohol solvent selected from methanol and ethanol, and a silane coupling agent and 12-hydroxystearic acid.
• a solvent replacement step of replacing the alcohol solvent, which is a dispersion medium of the alcohol dispersion, with an organic solvent other than the alcohol, preferably while containing titanium oxide particles at a high content rate In addition to low viscosity, there is no increase in viscosity over time, precipitation of particles, decrease in transparency, etc., and excellent stability and dispersion of titanium oxide particles with excellent transparency in organic solvent The body can be obtained easily and stably.
• the organic solvent dispersion of titanium oxide particles obtained by the present invention has the above-described characteristics, it has low viscosity, excellent stability and transparency, while containing titanium oxide particles at a high content. Desirable properties inherent to titanium oxide particles such as refractive index are not impaired. For example, various applications in the optical field, particularly as materials for optical composite resins such as LED sealing resins and antireflection films. It can be used suitably.
• the method for producing an organic solvent dispersion of titanium oxide particles according to the present invention is a method for producing an organic solvent dispersion of titanium oxide particles obtained by dispersing titanium oxide particles in an organic solvent excluding methanol and ethanol, (A) Treatment of an alcohol dispersion of titanium oxide particles obtained by dispersing titanium oxide particles in at least one alcohol solvent selected from methanol and ethanol with a surface treatment agent containing a silane coupling agent and 12-hydroxystearic acid And a surface treatment step for surface-treating the titanium oxide particles, (B) a solvent replacement step of replacing the alcohol solvent, which is a dispersion medium in the alcohol dispersion of the surface-treated titanium oxide particles, with an organic solvent other than the alcohol solvent;
• the silane coupling agent is represented by the general formula (I) (RO) n- Si-X 4-n (I) (In the formula, R represents an alkyl group having 1 to 4 carbon atoms, n represents 2 or 3, and X represents an alkyl group, a fluorinated alkyl
• the titanium oxide particles may be crystalline or amorphous, and in the case of being crystalline, rutile, anatase, brookite or A mixture of these may be used, and a mixture of crystalline and amorphous may be used.
• the D50 of the titanium oxide particles in the alcohol dispersion of the titanium oxide particles is preferably in the range of 1 to 20 nm so that the obtained organic solvent dispersion is excellent in transparency. More preferably, it is in the range. D90 is preferably 40 nm or less.
• the obtained organic solvent dispersion of titanium oxide particles contains titanium oxide particles at a high content of 10% by weight or more, has a low viscosity, and is excellent in stability and transparency.
• the transmittance at a wavelength of 500 nm is 40% or more
• the transmittance at a wavelength of 800 nm is 80% or more. Is preferred.
• the D50 of the titanium oxide particles in the dispersion of titanium oxide particles is 50% of the volume-based cumulative distribution value obtained from the particle size distribution of the titanium oxide particles in the dispersion measured by the dynamic light scattering method.
• the particle diameter at a certain time that is, the average particle diameter or the median diameter
• D90 and D100 refer to the particle diameters when the volume-based integrated distribution values are 90% and 100%, respectively.
• the content of the titanium oxide particles in the surface treatment of the alcohol dispersion of the titanium oxide particles is determined by the surface treatment of the titanium oxide particles with the surface treatment agent containing the silane coupling agent and 12-hydroxystearic acid. In order to carry out efficiently, it is usually in the range of 1 to 40% by weight, preferably in the range of 5 to 30% by weight.
• the alkyl group R having 1 to 4 carbon atoms represents a methyl group, an ethyl group, a propyl group, or a butyl group, and has 3 or 4 carbon atoms.
• a certain alkyl group may be linear or branched.
• X when X is an alkyl group, the number of carbon atoms is usually in the range of 1 to 20, preferably in the range of 1 to 12. Therefore, specific examples of such an alkyl group include a methyl group, an ethyl group, a propyl group, a hexyl group, a decyl group, and an undecyl group.
• the alkyl group having 3 or more carbon atoms may be linear or branched.
• silane coupling agent in which X is an alkyl group for example, methyltrimethoxysilane, methyltriethoxysilane, isobutyltrimethoxysilane, butyltrimethoxysilane, hexyltrimethoxysilane, Decyltrimethoxysilane, butyltriethoxysilane, isobutyltriethoxysilane, hexyltriethoxysilane, octyltriethoxysilane, decyltriethoxysilane, undecyltriethoxysilane, dimethyldimethoxysilane, diethyldimethoxysilane, diethyldiethoxysilane, etc. Can be mentioned.
• the alkyl group when X is a fluorinated alkyl group, the alkyl group usually has 1 to 18 carbon atoms, preferably 1 to 10 carbon atoms. Accordingly, specific examples of such a fluorinated alkyl group include trifluoromethyl, trifluoroethyl, trifluoropropyl, perfluorooctylethyl groups, and the like.
• silane coupling agent in which X is a fluorinated alkyl group for example, 3,3,3-trifluoropropyltrimethoxysilane, perfluorooctylethyltrimethoxysilane, perfluorooctylethyltriethoxysilane, perfluorooctyl Examples thereof include ethyl triisopropoxysilane.
• silane coupling agent represented by the general formula (I) when X is a vinyl group, specific examples include vinyltrimethoxysilane and vinyltriethoxysilane.
• examples of the silane coupling agent in which X is a (meth) acryloyloxyalkyl group include (meth) acryloyloxymethyltrimethoxysilane, (meth ) Acryloyloxymethyltriethoxysilane, 2- (meth) acryloyloxyethyltrimethoxysilane, 2- (meth) acryloyloxyethyltriethoxysilane, 3- (meth) acryloyloxypropyltrimethoxysilane, 3- (meth) acryloyl Examples thereof include oxypropyltriethoxysilane and 3-methacryloyloxypropylmethyldimethoxysilane.
• (Meth) acryloyl means acryloyl or methacryloyl.
• the surface treatment agent silane coupling agent and 12-hydroxystearic acid may be added to the alcohol dispersion of titanium oxide particles at the same time, or after either one is added first, Others may be added.
• one or both of the surface treatment agents described above is an appropriate organic solvent, for example, the same alcohol solvent as the dispersion medium of the alcohol dispersion of titanium oxide particles (hereinafter simply referred to as alcohol solvent A for the sake of simplicity). Or dissolved in the same organic solvent as the dispersion medium of the organic solvent dispersion of the target titanium oxide particles (hereinafter simply referred to as the organic solvent S for simplicity). The solution may be added to the alcohol dispersion. Moreover, after adding the said surface treating agent to the alcohol dispersion of a titanium oxide particle, you may add the said organic solvent S to a dispersion.
• alcohol solvent A the same alcohol solvent as the dispersion medium of the organic solvent dispersion of the target titanium oxide particles
• the surface treatment of the titanium oxide particles in the alcohol dispersion with the surface treatment agent containing the silane coupling agent and 12-hydroxystearic acid can be performed, for example, by the following method. .
• adding a solution obtained by dissolving the surface treatment agent in the organic solvent S to the alcohol dispersion of the titanium oxide particles, or adding the organic solvent S, namely, titanium oxide This means that the dispersion medium of the particle dispersion is changed to a mixture of alcohol and the organic solvent. Therefore, the dispersion of titanium oxide particles using the mixture of alcohol and the organic solvent S as a dispersion medium is used in the surface treatment agent. By processing, it means that the titanium oxide particles are surface-treated with the surface treatment agent.
• a method of treating the alcohol dispersion of titanium oxide particles with the surface treatment agent in the presence of the organic solvent, that is, a mixture of the alcohol and the organic solvent S is used as a dispersion medium.
• the method of treating the dispersion of titanium oxide particles to be treated with the surface treatment agent is one of the methods that can be preferably used in the surface treatment step in the present invention.
• the surface treatment agent is used so as to contain 1 to 40 parts by weight of the silane coupling agent and 1 to 80 parts by weight of 12-hydroxystearic acid with respect to 100 parts by weight of the titanium oxide particles.
• the silane coupling agent is preferably used in the range of 1 to 10 parts by weight with respect to 100 parts by weight of the titanium oxide particles in the alcohol dispersion of titanium oxide particles.
• 12-hydroxystearic acid is preferably used in the range of 1 to 10 parts by weight with respect to 100 parts by weight of titanium oxide particles in the alcohol dispersion of titanium oxide particles.
• the surface treatment agent preferably comprises only the silane coupling agent and 12-hydroxystearic acid. That is, in the present invention, the surface treatment agent preferably does not contain any surface treatment agent other than the silane coupling agent and 12-hydroxystearic acid.
• the total amount of the silane coupling agent and 12-hydroxystearic acid is 2 to 20 weights per 100 weight parts of the titanium oxide particles in the alcohol dispersion of titanium oxide particles. It is preferably used in a range of 5 parts by weight, and more preferably in a range of 5 to 20 parts by weight.
• the surface treatment step of surface-treating the titanium oxide particles in the alcohol dispersion of titanium oxide particles with the surface treatment agent, and the dispersion medium of the alcohol dispersion of the surface-treated titanium oxide particles is obtained by performing a solvent substitution step of substituting the alcohol solvent with the organic solvent.
• the solvent replacement step may be performed after the surface treatment step, or the solvent replacement step may be performed while performing the surface treatment step.
• a silane coupling agent and 12-hydroxystearic acid are added to an alcohol dispersion of titanium oxide particles under normal temperature and normal pressure, mixed and stirred, and the titanium oxide particles are mixed. If the organic solvent is continuously or intermittently added to the alcohol dispersion and the solvent is replaced with the alcohol solvent that is the dispersion medium of the alcohol dispersion, the target is obtained. An organic solvent dispersion can be obtained.
• a silane coupling agent and 12-hydroxystearic acid are dissolved in an organic solvent S, and the obtained solution is dispersed in alcohol of titanium oxide particles.
• a silane coupling agent, 12-hydroxystearic acid and organic solvent S are added to the alcohol dispersion of titanium oxide particles, and the resulting dispersion of titanium oxide particles is added in the presence of the organic solvent, that is, In a dispersion of titanium oxide particles using a mixture of an alcohol and the organic solvent S as a dispersion medium, the titanium oxide particles are surface-treated with the surface treatment agent, and then the solvent is replaced. By removing the alcohol, a desired organic solvent dispersion can be obtained.
• This method is one of the methods that can be preferably used in the solvent replacement step.
• a silane coupling agent and 12-hydroxystearic acid are dissolved in an organic solvent S, and the resulting solution is added to an alcohol dispersion of titanium oxide particles, or a silane coupling agent and 12 -Hydroxystearic acid and organic solvent S are added to an alcohol dispersion of titanium oxide particles, and the resulting dispersion of titanium oxide particles is added to the dispersion medium in the presence of the organic solvent, that is, the mixture of alcohol and organic solvent S.
• the alcohol is removed from the dispersion and the solvent is replaced.
• a solvent dispersion can be obtained.
• the organic solvent that is a dispersion medium in the organic solvent dispersion of titanium oxide particles is preferably an organic solvent that is more lipophilic than methanol and ethanol.
• an organic solvent that is more lipophilic organic solvent include the number of carbon atoms. Examples thereof include three or more alcohols, glycols, ketones, ketone alcohols, esters, ethers, hydrocarbons, carbon halides, carboxylic acid amides, sulfoxides, and the like.
• alcohols having 3 or more carbon atoms include propanols such as isopropanol and butanols such as 1-butanol, and glycols include ethylene glycol and propylene glycol as ketones.
• MK methyl ethyl ketone
• MIBK methyl isobutyl ketone
• ketone alcohols are diacetone alcohol
• esters are ethyl acetate, butyl acetate
• propylene glycol monomethyl ether Acetate, diethylene glycol monoethyl ether acetate, methyl acrylate, methyl methacrylate, etc.
• ethers include dibutyl ether, propylene glycol monomethyl ether, dioxa As hydrocarbons, n-hexane, cyclohexane, toluene, xylene, solvent naphtha,
• preferred lipophilic organic solvents include methyl isobutyl ketone, methyl ethyl ketone, diacetone alcohol, butanol, propanol, propylene glycol monomethyl ether, toluene, dimethyl sulfoxide, N, N-dimethylacetamide, N, N, There may be mentioned at least one selected from 2-trimethylpropionamide, ⁇ -butyrolactone and butyl acetate.
• the method in order to replace the alcohol solvent, which is a dispersion medium of the alcohol dispersion of titanium oxide particles, with the above lipophilic organic solvent other than the alcohol solvent, the method itself is a well-known distillation substitution method or a limitation. It can be performed by an outer filtration concentration substitution method.
• the distillation substitution method is a dispersion medium of the above-described alcohol dispersion by heating an alcohol dispersion of titanium oxide particles surface-treated with a surface treatment agent to a temperature equal to or higher than the boiling point of the alcohol as the dispersion medium.
• the target organic solvent is added to the dispersion while distilling and removing the alcohol from the dispersion.
• an alcohol dispersion of titanium oxide particles surface-treated with the surface treatment agent is heated under normal pressure or reduced pressure, and the alcohol solvent is distilled, preferably at the same rate as the distillation rate.
• the alcohol solvent that is a dispersion medium of the alcohol dispersion of the titanium oxide particles can be replaced with the organic solvent.
• the surface treatment agent is dissolved in the organic solvent, and the resulting solution is added to the alcohol dispersion of titanium oxide particles, or the surface treatment agent and
• the organic solvent is added to the alcohol dispersion of titanium oxide particles, and the titanium oxide particles are surface-treated with the surface treatment agent in the presence of the organic solvent, and then heated under normal pressure or reduced pressure to form the alcohol dispersion.
• the alcohol that is the dispersion medium is removed by distillation, and the alcohol solvent that is the dispersion medium of the alcohol dispersion of the titanium oxide particles can be replaced with the organic solvent.
• the organic solvent to be used has a boiling point equal to or higher than that of the alcohol under the distillation conditions. It is desirable.
• an alcohol dispersion of titanium oxide particles is subjected to ultrafiltration, the alcohol solvent is permeated through a membrane, and the alcohol is removed from the dispersion.
• the target organic solvent is added, and thus the alcohol solvent, which is the dispersion medium of the alcohol dispersion of the titanium oxide particles, is replaced with the organic solvent.
• the obtained alcohol dispersion is pumped to an ultrafiltration module, and the alcohol solvent is passed through the membrane by allowing the alcohol solvent to pass through the membrane.
• the target organic solvent is added stepwise or continuously to the dispersion to replace the alcohol solvent, which is a dispersion medium of the alcohol dispersion of titanium oxide particles, with the organic solvent.
• the transmittance at a wavelength of 800 nm is 70% or more, preferably the transmittance at a wavelength of 550 nm is 4% or more, and the transmittance at a wavelength of 600 nm is 8% or more.
• an organic solvent dispersion having a viscosity immediately after production of 10 mPa ⁇ s or less and an increase in viscosity after 7 days with respect to the viscosity immediately after production is 40 mPa ⁇ s or less can be obtained.
• the method of the present invention after surface-treating the titanium oxide particles in the alcohol dispersion of the titanium oxide particles used as a starting material with the surface treatment agent described above or while surface-treating with the surface treatment agent, by substituting the alcohol solvent, which is a dispersion medium, with the organic solvent, a fine average particle diameter D50 of the titanium oxide particles in the alcohol dispersion is inherited by the organic solvent dispersion of titanium oxide particles. It is possible to obtain an organic solvent dispersion of titanium oxide particles having a small D50 of the titanium oxide particles therein and having low viscosity and high stability and transparency.
• the organic solvent dispersion of titanium oxide particles obtained by the present invention has low viscosity, excellent stability and transparency while containing titanium oxide particles in a high content, and the titanium oxide particles are Originally, it has desirable characteristics.
• the alcohol dispersion of titanium oxide particles used in the surface treatment step may be a commercially available product.
• the alcohol dispersion of titanium oxide particles used in the surface treatment step is peptized by adding acid to the titanium oxide water slurry, and wet-dispersed to obtain an aqueous dispersion.
• Acetic acid and nitric acid are used in combination as the acid to obtain an aqueous dispersion, and then the dispersion medium of the aqueous dispersion is replaced with the alcohol, and thus an alcohol dispersion obtained in this manner is preferable.
• an alcohol dispersion of titanium oxide particles that can be preferably used, (A) a step of wet dispersion treatment of an aqueous slurry of titanium oxide particles in the presence of acetic acid and nitric acid with a medium stirring mill or a high-pressure disperser to obtain an aqueous dispersion of titanium oxide particles; (B) a step of washing the aqueous dispersion of titanium oxide particles obtained in the step (a), (C) a step of replacing water, which is a dispersion medium of the aqueous dispersion of titanium oxide particles obtained in the step (b), with at least one alcohol solvent selected from methanol and ethanol; Can be obtained by a method comprising
• the water slurry of titanium oxide particles used as a starting material is not particularly limited in its origin. Therefore, in the present invention, for example, an aqueous slurry of titanium oxide particles obtained by dispersing titanium oxide powder in water can also be used.
• the water slurry of titanium oxide particles used as a starting material is preferably obtained by the following method, for example.
• a titanium oxide water slurry used as a starting material is prepared by the following method: (1) After adjusting the chlorine ion concentration of the aqueous solution of titanium tetrachloride to 0.5 mol / L or more and less than 4.4 mol / L, the solution is heated at a temperature in the range of 25 to 75 ° C.
• the first step is a step of hydrolyzing titanium tetrachloride in water to precipitate rutile titanium oxide particles to obtain a slurry containing such rutile titanium oxide particles. That is, in the first step, the titanium tetrachloride aqueous solution is in the range of 10 to 100 g / L as titanium oxide (TiO 2 , hereinafter the same), and the chlorine concentration is 0.5 mol / L or more. After adjusting by adding water to the titanium tetrachloride aqueous solution so as to be less than 4 mol / L, it is heated at a temperature in the range of 25 to 75 ° C. for 1 to 10 hours. Titanium chloride is hydrolyzed to deposit rutile titanium oxide particles.
• titanium tetrachloride When the hydrolysis temperature of titanium tetrachloride exceeds 75 ° C., the anatase type is added to the titanium tetrachloride hydrolyzate even if the chlorine ion concentration is in the range of 0.5 mol / L or more and less than 4.4 mol / L. Titanium oxide and brookite type titanium oxide may be mixed.
• the hydrolysis rate of titanium tetrachloride depends on the hydrolysis temperature, and the higher the temperature, the faster the hydrolysis rate, which is industrially advantageous.
• the hydrolysis rate of titanium tetrachloride is lower than 25 ° C., it is difficult to hydrolyze the titanium tetrachloride aqueous solution at a practical rate.
• the first step in particular, after adjusting the titanium tetrachloride aqueous solution by adding water so that the chlorine concentration of the titanium tetrachloride aqueous solution is 1.0 mol / L or more and 4.3 mol / L or less, although not limited to a temperature in the range of 30 to 75 ° C., it is preferable to heat for 1 to 5 hours to hydrolyze titanium tetrachloride to precipitate rutile titanium oxide particles.
• the slurry obtained in the second step is hydrothermally reacted in the presence of an organic acid as a particle growth inhibitor to increase crystallinity while suppressing the growth of rutile titanium oxide particles.
• an organic acid carboxylic acid or hydroxycarboxylic acid
• the carboxylic acid or hydroxycarboxylic acid may be a salt.
• organic acids include, for example, monocarboxylic acids such as formic acid, acetic acid and propionic acid and salts thereof, polybasic acids such as oxalic acid, malonic acid, succinic acid, fumaric acid and maleic acid and salts thereof.
• the organic acid as described above is used in an amount of 75 parts by mole or more with respect to 100 parts by mole of titanium oxide, thereby suppressing the growth of the rutile-type titanium oxide particles obtained by the hydrothermal reaction. Can be effectively increased.
• the amount of the organic acid is less than 75 mole parts relative to 100 mole parts of titanium oxide, the effect of suppressing the growth of rutile titanium oxide particles is not observed in the hydrothermal reaction.
• a more preferable amount of the organic acid with respect to 100 mol parts of titanium oxide is 85 mol parts or more.
• the upper limit of the amount of organic acid relative to titanium oxide is not particularly limited, but since the effect of increasing the crystallinity of rutile-type titanium oxide particles is not changed even when an excessive amount is used, the amount of organic acid is usually 200 mol parts or less is sufficient with respect to 100 mol parts of titanium oxide.
• a suitable alkali for example, a sodium hydroxide aqueous solution is added to the aqueous slurry of titanium oxide particles obtained by the hydrothermal reaction in the third step, and the organic acid in the aqueous slurry is added to the aqueous slurry.
• the obtained water slurry is filtered and washed, water-soluble salts dissolved in the water slurry are removed, and the obtained titanium oxide particles are repulped into water to obtain the desired titanium oxide particles.
• the means and method for filtering and washing the water slurry of titanium oxide particles are not limited at all, but as described above, it is suitable for the water slurry obtained by hydrothermal reaction.
• the aqueous slurry of titanium oxide particles is subjected to the steps (a) to (c) as described above.
• the water slurry obtained in the fourth step of the above-described titanium oxide particle water slurry production process is peptized in the presence of acetic acid and nitric acid, and then wet dispersed to obtain an aqueous dispersion. It is the process of obtaining.
• acetic acid and nitric acid are added to an aqueous slurry of titanium oxide particles to peptize the titanium oxide particles, and then wet dispersion treatment is performed.
• water which is the dispersion medium of the aqueous slurry of titanium particles
• alcohol even if the proportion of alcohol as the dispersion medium increases in the resulting dispersion, the aggregation of titanium oxide particles in the dispersion is suppressed and dispersed.
• An alcohol dispersion of titanium oxide particles having excellent properties and transparency can be obtained.
• the titanium oxide particles When only the nitric acid is added to the water slurry of titanium oxide particles, the titanium oxide particles are peptized, and then wet dispersion treatment is performed.
• the water that is the dispersion medium of the water slurry is replaced with alcohol, As the proportion of alcohol as the dispersion medium increases, the titanium oxide particles in the dispersion aggregate and the dispersibility and transparency are impaired.
• the viscosity of the dispersion increases as the water-soluble salts are removed in the step (b). It rises and eventually loses its fluidity and gels.
• acetic acid when acetic acid and nitric acid are added to an aqueous slurry of titanium oxide particles to peptize the titanium oxide particles, acetic acid is in a range of 15 to 250 mol parts with respect to 100 mol parts of titanium oxide. Are preferably used in the range of 15 to 90 parts by mole.
• the wet dispersion treatment in the step (a) uses a medium stirring mill or a high-pressure disperser, and for example, a bead mill is preferably used as the medium stirring mill.
• a bead mill is preferably used as the medium stirring mill.
• the beads those having a Mohs hardness higher than that of titania are preferable.
• zirconia beads are preferably used. According to a preferred embodiment, zirconia beads having a diameter of 15 to 300 ⁇ m are charged into a bead mill and dispersed to obtain an aqueous dispersion of rutile-type titanium oxide particles.
• the step (b) is a step of removing water-soluble salts dissolved in the aqueous dispersion in order to give dispersion stability to the aqueous dispersion of titanium oxide particles obtained in the step (a).
• the means and method for removing the water-soluble salts dissolved in the aqueous dispersion are not particularly limited, and for example, dialysis or ultrafiltration can be used.
• the titanium oxide aqueous dispersion obtained in the step (a) contains acetic acid and nitric acid used as a peptizer, its electrical conductivity is usually greater than 10 mS / cm.
• the electric conductivity of the aqueous dispersion is in the range of 0.1 to 5 mS / cm, preferably in the range of 1 to 3 mS / cm, the aqueous dispersion having excellent dispersion stability of the rutile titanium oxide particles. You can get a body.
• titanium tetrachloride is hydrolyzed in an aqueous solution to precipitate rutile-type titanium oxide particles, which are hydrothermally treated in the presence of an organic acid, while suppressing particle growth. Then, the crystallinity is improved, and then the water slurry of the rutile-type titanium oxide particles obtained in this way is added with a combination of acetic acid and nitric acid to peptize, followed by wet dispersion treatment, and further with excess acid. By removing the dissolved water-soluble salts, it is possible to obtain an aqueous dispersion that is stably dispersed in water without aggregation of the rutile titanium oxide particles.
• the titanium oxide particle content is 10% by weight or more
• the D50 of the titanium oxide particles is 1 in the particle size distribution measured by the dynamic light scattering method.
• transmittance at a wavelength of 500 nm is 50% or more
• transmittance at a wavelength of 800 nm is 90% or more
• An aqueous dispersion of titanium oxide particles having a viscosity of 20 mPa ⁇ s or less, preferably 10 mPa ⁇ s or less, can be obtained.
• an alcohol dispersion of titanium oxide particles that is, containing 10% by weight or more of titanium oxide particles, D50 in the range of 1 to 20 nm, preferably in the range of 2 to 10 nm, D90 of 40 nm or less, at a wavelength of 500 nm Alcohol dispersion of titanium oxide particles having a transmittance of 40% or more, a transmittance at a wavelength of 800 nm of 80% or more, and a viscosity immediately after production at a temperature of 25 ° C. of 20 mPa ⁇ s or less, preferably 10 mPa ⁇ s or less You can get a body.
• the following reference examples show preparation examples of an aqueous dispersion and an alcohol dispersion of titanium oxide particles.
• “Microza” model ACP-1010D, molecular weight cut off 13000 manufactured by Asahi Kasei Chemicals Corporation was used for ultrafiltration.
• the following examples and comparative examples show preparation examples of an organic solvent dispersion of titanium oxide particles using the alcohol dispersion of titanium oxide particles obtained in the above reference example.
• the dispersion diameter of the titanium oxide particles in the aqueous dispersion, alcohol dispersion and organic solvent dispersion of the titanium oxide particles that is, the size (diameter) of the particles dispersed in the dispersion, Turbidimeter transmittance, transmittance and viscosity at wavelengths of 500 nm, 550 nm, 600 nm and 800 nm were measured as follows.
• the dispersion diameter of the titanium oxide particles was measured by a dynamic light scattering method (UPA-UT manufactured by Nikkiso Co., Ltd.).
• the turbidimeter transmittance was measured by using a haze meter (NDH4000 manufactured by Nippon Denshoku Industries Co., Ltd.) to fill a cell with an optical path length of 10 mm with ion-exchanged water and measuring the total light transmittance (blank value) T 0.
• the cell was filled with the dispersion, and the light transmittance T was measured to obtain (T / T 0 ) ⁇ 100.
• the transmittance at wavelengths of 500 nm, 550 nm, 600 nm, and 800 nm was measured with a visible ultraviolet spectrophotometer (manufactured by JASCO Corporation V-570) after filling the dispersion with a cell having an optical path length of 10 mm.
• Viscosity was measured with a tuning-fork vibration type SV viscometer (A & D Co., Ltd. Sakai SV-1A (measured viscosity range: 0.3 to 1000 mPa ⁇ s)).
• Reference example 1 Preparation of aqueous dispersion (I) of rutile-type titanium oxide particles
• a separable flask equipped with a reflux apparatus was charged with 3 L of a titanium tetrachloride aqueous solution adjusted to 50.7 g / L as titanium oxide based on a chlorine ion concentration of 2.3 mol / L and a titanium ion concentration, and 70 ° C. was heated for 3 hours and hydrolyzed to obtain a water slurry containing precipitated rutile titanium oxide particles.
• the water slurry was filtered using a glass fiber filter with a collection diameter of 300 nm to remove unreacted titanium tetrachloride and dissolved components.
• the titanium oxide particles thus obtained are repulped into water, and an aqueous sodium hydroxide solution is added to the obtained water slurry until the pH of the water slurry becomes 7.0, and then a glass fiber filter paper having a collection diameter of 300 nm. And filtered.
• the rutile titanium oxide is repulped into water so as to be 50 g / L as titanium oxide, it is filtered and washed with water until the electrical conductivity of the slurry becomes 100 ⁇ S / cm or less to remove water-soluble salts. did. *
• the mixture After adding an aqueous sodium hydroxide solution to the slurry obtained by the hydrothermal reaction until the pH becomes 5.0, the mixture is filtered using a glass fiber filter with a collection diameter of 300 nm.
• rutile type titanium oxide particles When water is repulped as titanium oxide to 100 g / L, the slurry is filtered and washed with water until the electrical conductivity of the slurry is 100 ⁇ S / cm or less to remove water-soluble salts, and thus the rutile thus obtained.
• the titanium oxide particles were repulped into water so as to be 100 g / L as titanium oxide to obtain an aqueous slurry of titanium oxide particles. (4th process)
• aqueous dispersion (I) of titanium oxide particles has a transmittance of 65.1% at a wavelength of 500 nm and a transmittance of 95.9% at a wavelength of 800 nm.
• the viscosity was 2 mPa ⁇ s.
• the dispersion diameter D50 of the titanium oxide particles in the aqueous dispersion (I) of the titanium oxide particles was 4 nm, and D90 was 6.4 nm. Therefore, it was found that the titanium oxide particles were hardly aggregated in the obtained aqueous dispersion (I) of titanium oxide particles.
• Step (II) Preparation of methanol dispersion of titanium oxide (II)) Concentrating and diluting with methanol continuously and simultaneously in parallel by concentrating 500 g of the titanium oxide particle aqueous dispersion (I) using an ultrafiltration membrane and introducing methanol in an amount equal to the amount of the concentrated filtrate. By replacing the dispersion medium of the dispersion from water to methanol while maintaining the content of titanium oxide particles in the dispersion at 15% by weight (step (c)), the content of titanium oxide particles is 15% by weight. A methanol dispersion (II) of titanium oxide was obtained. At this time, the amount of methanol used for dilution was 2 L.
• the thus obtained methanol dispersion (II) of titanium oxide particles has a transmittance of 57% at a wavelength of 500 nm, a transmittance of 95% at a wavelength of 800 nm, and a viscosity immediately after production at a temperature of 25 ° C. 1 mPa ⁇ s.
• the obtained titanium oxide particles were dried.
• the average primary particle diameter of the titanium oxide particles was about 4 nm.
• the dispersion diameter D50 of the titanium oxide particles in the methanol dispersion (II) of the titanium oxide particles was 4 nm, and D90 was 9.2 nm. Therefore, it was found that in the obtained methanol dispersion (II) of titanium oxide particles, almost no aggregation of titanium oxide particles occurred.
• Reference example 2 Preparation of water dispersion (III) of anatase-type titanium oxide particles
• An anatase-type titanium oxide particle water slurry (CSB-M) manufactured by Sakai Chemical Industry Co., Ltd. was diluted with water to make the titanium oxide content 100 g / L.
• To this aqueous slurry of titanium oxide particles 150 mol parts of acetic acid and 50 mol parts of nitric acid were added to 100 mol parts of titanium oxide, and peptized.
• the aqueous slurry of titanium oxide particles thus obtained was subjected to a wet dispersion treatment for 10 hours using a circulating bead mill “Ultra Apex Mill UAM-05” manufactured by Kotobuki Industries Co., Ltd.
• An aqueous dispersion was obtained.
• zirconia beads having a diameter of 30 ⁇ m were used, and the rotation speed of the bead mill was set to 2350 rpm.
• aqueous dispersion (III) of titanium oxide particles has a transmittance of 77.2% at a wavelength of 500 nm and a transmittance of 97.2% at a wavelength of 800 nm.
• the viscosity was 3 mPa ⁇ s.
• the average primary particle diameter of the titanium oxide particles was about 5 nm.
• the dispersion diameter D50 of the titanium oxide particles in the aqueous dispersion (III) of the titanium oxide particles was 5 nm, and D90 was 5.8 nm. Therefore, it was found that the titanium oxide particles were hardly aggregated in the obtained aqueous dispersion (III) of titanium oxide particles.
• Step (IV) Preparation of methanol dispersion of titanium oxide (IV)) Concentrating and diluting with methanol continuously and simultaneously in parallel by concentrating 500 g of the titanium oxide aqueous dispersion (III) using an ultrafiltration membrane and introducing methanol in an amount equal to the amount of the concentrated filtrate. By replacing the dispersion medium of the dispersion from water to methanol (step (c)) while maintaining the titanium oxide particle content in the dispersion at 15% by weight, oxidation with a titanium oxide particle content of 15% by weight is performed. A titanium methanol dispersion (IV) was obtained. At this time, the amount of methanol used for dilution was 2 L.
• the methanol dispersion (IV) of titanium oxide particles thus obtained has a transmittance of 66% at a wavelength of 500 nm, a transmittance of 96% at a wavelength of 800 nm, and a viscosity immediately after production at a temperature of 25 ° C. 1 mPa ⁇ s.
• the obtained titanium oxide particles were dried.
• the average primary particle diameter of the titanium oxide particles was about 5 nm.
• the dispersion diameter D50 of the titanium oxide particles in the methanol dispersion (IV) of the titanium oxide particles was 5 nm, and D90 was 6.2 nm. Therefore, it was found that in the obtained methanol dispersion (IV) of titanium oxide particles, aggregation of the titanium oxide particles hardly occurred.
• Solvent substitution rate A sample was prepared by dissolving the obtained dispersion in deuterated chloroform, and a one-dimensional NMR spectrum of proton was measured for this sample using a nuclear magnetic resonance apparatus (AV400M manufactured by Bruker BioSpin Corporation). Based on this, the area ratio (substance ratio) of each solvent peak was converted to a mass ratio to calculate the solvent ratio, and the solvent substitution rate was determined based on this solvent ratio.
• HSA in the column of surface treatment agent represents 12-hydroxystearic acid
• (a) to (m) in the column of silane coupling agent are the silane coupling agents used.
• the numerical value in the column of the surface treatment agent indicates the number of parts by weight of the used surface treatment agent with respect to 100 parts by weight of titanium oxide.
• Silane coupling agents (a) to (m) represent the following silane coupling agents.
• (k) N-2- (aminoethyl) -3-aminopropyltrimethoxysilane
• Example 1 To 100 g of the methanol dispersion (II) of titanium oxide particles obtained in Reference Example 1, 1.5 g of 3-methacryloyloxypropyltrimethoxysilane (10.0 parts by weight with respect to 100 parts by weight of titanium oxide) and 12-hydroxy Stearic acid (1.5 g) (10.0 parts by weight with respect to 100 parts by weight of titanium oxide) was added, the mixture was stirred at a temperature of 26 ° C. for 5 minutes, and the dispersion was treated with the surface treatment agent.
• the methanol dispersion of titanium oxide particles treated in this manner is heated under normal pressure to distill methanol, and MEK is added dropwise to the dispersion at the same rate as the methanol distillation rate, and a solvent is added. Substitution was performed to obtain a MEK dispersion of titanium oxide particles having a titanium oxide particle content of about 15% by weight.
• Example 2 To 100 g of the methanol dispersion (II) of titanium oxide particles obtained in Reference Example 1, 1.5 g of 3-methacryloyloxypropyltrimethoxysilane (10.0 parts by weight with respect to 100 parts by weight of titanium oxide) and 12-hydroxy After adding 1.5 g of stearic acid (10.0 parts by weight with respect to 100 parts by weight of titanium oxide), MEK was added, and the resulting dispersion of titanium oxide particles in methanol and MEK was heated at 24 ° C. for 5 minutes. The dispersion was treated with a surface treatment agent with stirring.
• the dispersion of titanium oxide particles treated in this way is heated under normal pressure to perform solvent replacement by distilling methanol to obtain a MEK dispersion of titanium oxide particles having a titanium oxide particle content of about 15% by weight. Obtained.
• solvent replacement method 2 As described above, after adding a surface treatment agent to a methanol dispersion of titanium oxide particles, an organic solvent is added, and thus the resulting dispersion is treated with the surface treatment agent, and then methanol is distilled under normal pressure.
• the solvent replacement method is referred to as solvent replacement method 2.
• Example 3 To 100 g of the methanol dispersion (II) of titanium oxide particles obtained in Reference Example 1, 1.5 g of 3-methacryloyloxypropyltrimethoxysilane (10.0 parts by weight with respect to 100 parts by weight of titanium oxide) and 12-hydroxy After adding 1.5 g of stearic acid (10.0 parts by weight with respect to 100 parts by weight of titanium oxide), MEK was added, and the resulting dispersion of titanium oxide particles in methanol and MEK was stirred at a temperature of 25 ° C. for 5 minutes. The dispersion was treated with a surface treatment agent with stirring.
• the dispersion of titanium oxide particles treated in this manner is heated under reduced pressure to perform solvent replacement by distilling methanol to obtain a MEK dispersion of titanium oxide particles having a titanium oxide particle content of about 15% by weight. It was.
• solvent replacement method 3 As described above, after adding the surface treatment agent to the methanol dispersion of titanium oxide particles, an organic solvent is added, and thus the resulting dispersion is treated with the surface treatment agent, and then methanol is distilled under reduced pressure.
• the solvent replacement method is referred to as solvent replacement method 3.
• Example 4 1.5 g of 3-methacryloyloxypropyltrimethoxysilane dissolved in MEK in 100 g of methanol dispersion (II) of titanium oxide particles obtained in Reference Example 1 above (10.0 parts by weight with respect to 100 parts by weight of titanium oxide) ) And 1.5 g of 12-hydroxystearic acid (10.0 parts by weight with respect to 100 parts by weight of titanium oxide), and the resulting dispersion of methanol and MEK of titanium oxide particles was stirred at a temperature of 24 ° C. for 5 minutes. And it processed with the said surface treating agent.
• methanol dispersion (II) of titanium oxide particles obtained in Reference Example 1 above (10.0 parts by weight with respect to 100 parts by weight of titanium oxide)
• 12-hydroxystearic acid 10.0 parts by weight with respect to 100 parts by weight of titanium oxide
• the dispersion of titanium oxide particles treated in this manner is heated under normal pressure, and solvent replacement is performed by distilling methanol to obtain a MEK dispersion of titanium oxide particles having a titanium oxide particle content of about 15% by weight. It was.
• the surface treatment agent is dissolved in the organic solvent, and the resulting solution is added to the methanol dispersion of titanium oxide particles.
• methanol is distilled.
• the solvent replacement method is referred to as solvent replacement method 4.
• Examples 5 to 37 A silane coupling agent and 12-hydroxystearic acid (and an organic solvent) in the amounts shown in Table 1 and Table 2 were added to 100 g of the methanol dispersion (II) of titanium oxide particles obtained in Reference Example 1 above, respectively. The resulting dispersion of titanium oxide particles in methanol (and of an organic solvent) was stirred at the temperatures shown in Tables 1 and 2 for 5 minutes, and the dispersion was treated with the surface treatment agent.
• the titanium oxide particle dispersion treated in this way was subjected to solvent substitution in the solvent substitution method 1, 2, 3 or 4, and the titanium oxide particle content was about 15% by weight.
• An organic solvent dispersion of titanium oxide particles was obtained.
• Examples 38 and 39 The silane coupling agent and 12-hydroxystearic acid (and organic solvent) in the amounts shown in Table 2 were added to 100 g of the methanol dispersion (IV) of titanium oxide particles obtained in Reference Example 2 above, and the resulting oxidation was obtained.
• the methanol (and organic solvent) dispersion of titanium particles was stirred at the temperature shown in Table 2 for 5 minutes, and the dispersion was treated with the surface treatment agent.
• the dispersion of titanium oxide particles treated in this manner was subjected to solvent substitution by the solvent substitution method shown in Table 2 to obtain an organic solvent dispersion of titanium oxide particles having a titanium oxide particle content of about 15% by weight.
• Comparative Example 1 By adding only MEK to the methanol dispersion (II) of titanium oxide particles obtained in Reference Example 1 above without adding any of 3-methacryloyloxypropyltrimethoxysilane and 12-hydroxystearic acid, the resulting oxidation was obtained. A dispersion of titanium particles in methanol and MEK was stirred at a temperature of 23 ° C. for 5 minutes.
• Comparative Example 2 After adding 1.5 g of 3-methacryloyloxypropyltrimethoxysilane (10.0 parts by weight with respect to 100 parts by weight of titanium oxide) to 100 g of methanol dispersion (II) of titanium oxide particles obtained in Reference Example 1 above. MEK was added, and the resulting dispersion of titanium oxide particles in methanol and MEK was stirred at a temperature of 24 ° C. for 5 minutes, and the dispersion was treated with the surface treatment agent.
• methanol dispersion II
• Comparative Example 3 After adding 1.5 g of 12-hydroxystearic acid (10.0 parts by weight with respect to 100 parts by weight of titanium oxide) to 100 g of methanol dispersion (II) of titanium oxide particles obtained in Reference Example 1, MEK was added. In addition, the resulting dispersion of titanium oxide particles in methanol and MEK was stirred at a temperature of 25 ° C. for 5 minutes, and the dispersion was treated with the surface treatment agent.
• Comparative Example 4 After adding 3 g of 3-methacryloyloxypropyltrimethoxysilane (20.0 parts by weight with respect to 100 parts by weight of titanium oxide) to 100 g of methanol dispersion (II) of the titanium oxide particles obtained in Reference Example 1, MEK was added. And a dispersion of methanol and MEK of the obtained titanium oxide particles was stirred at a temperature of 26 ° C. for 5 minutes, and the dispersion was treated with the surface treatment agent.
• Comparative Examples 5-7 Obtained by adding MEK to 100 g of methanol dispersion (II) of titanium oxide particles obtained in Reference Example 1 in the amounts shown in Table 5 and / or one of 12-hydroxystearic acid and MEK. The dispersion of titanium oxide particles in methanol and MEK was stirred for 5 minutes each at the temperature shown in Table 5, and the dispersion was treated with the surface treatment agent.
• methanol dispersion (II) of titanium oxide particles obtained in Reference Example 1 in the amounts shown in Table 5 and / or one of 12-hydroxystearic acid and MEK.
• the dispersion of titanium oxide particles in methanol and MEK was stirred for 5 minutes each at the temperature shown in Table 5, and the dispersion was treated with the surface treatment agent.
• Comparative Examples 8 and 9 The amount of silane coupling agent, 12-hydroxystearic acid and MEK shown in Table 5 was added to 100 g of the methanol dispersion (II) of titanium oxide particles obtained in Reference Example 1 above, and methanol in the resulting titanium oxide particles was added. Each of the dispersions of MEK and MEK was stirred at the temperatures shown in Table 5 for 5 minutes, and the dispersion was treated with the surface treatment agent.
• the dispersion of titanium oxide particles thus treated was subjected to solvent substitution by solvent substitution method 3 to obtain an organic solvent dispersion of titanium oxide particles having a titanium oxide particle content of about 15% by weight. did.
• the dispersion of titanium oxide particles treated in this manner was subjected to solvent substitution by solvent substitution method 3 to obtain a MEK dispersion of titanium oxide particles having a titanium oxide particle content of about 15% by weight. did.
• Comparative Example 11 After adding 1.5 g of 3-methacryloyloxypropyltrimethoxysilane (10.0 parts by weight with respect to 100 parts by weight of titanium oxide) to 100 g of methanol dispersion (II) of titanium oxide particles obtained in Reference Example 1 above. Then, MIBK was added, and the resulting dispersion of titanium oxide particles in methanol and MIBK was stirred at a temperature of 24 ° C. for 5 minutes, and the dispersion was treated with the surface treatment agent.
• Comparative Example 12 After adding 1.5 g of 12-hydroxystearic acid (10.0 parts by weight with respect to 100 parts by weight of titanium oxide) to 100 g of methanol dispersion (II) of titanium oxide particles obtained in Reference Example 1, MIBK was added. In addition, the obtained dispersion of titanium oxide particles in methanol and MIBK was stirred at a temperature of 17 ° C. for 5 minutes, and the dispersion was treated with the surface treatment agent.
• Comparative Example 13 100 g of methanol dispersion (II) of titanium oxide particles obtained in Reference Example 1 was heated under normal pressure to completely distill methanol, and then the residue was dried to obtain titanium oxide powder.
• Comparative Example 14 To 100 g of the methanol dispersion (II) of titanium oxide particles obtained in Reference Example 1, 1.5 g of 3-methacryloyloxypropyltrimethoxysilane (10.0 parts by weight with respect to 100 parts by weight of titanium oxide) and 12-hydroxy Stearic acid 1.5 g (10.0 parts by weight with respect to 100 parts by weight of titanium oxide) was added and stirred at a temperature of 25 ° C. for 5 minutes to treat the dispersion with the surface treatment agent.
• the titanium oxide powder thus obtained was added to MEK, stirred, and allowed to stand. As a result, titanium oxide particles settled and a MEK dispersion could not be obtained.
• Comparative Example 15 To 100 g of the methanol dispersion (II) of titanium oxide particles obtained in Reference Example 1, 1.5 g of 3-methacryloyloxypropyltrimethoxysilane (10.0 parts by weight with respect to 100 parts by weight of titanium oxide) and acetic acid 1. 5 g (10.0 parts by weight with respect to 100 parts by weight of titanium oxide) was added, the mixture was stirred at a temperature of 20 ° C. for 5 minutes, and the dispersion was treated with the surface treatment agent.
• Comparative Example 16 To 100 g of the methanol dispersion (II) of titanium oxide particles obtained in Reference Example 1 above, 12 g of 3-methacryloyloxypropyltrimethoxysilane (80.0 parts by weight with respect to 100 parts by weight of titanium oxide) and 12-hydroxystearic acid 1.5 g (10.0 parts by weight with respect to 100 parts by weight of titanium oxide) was added, the mixture was stirred at a temperature of 24 ° C. for 5 minutes, and the dispersion was treated with the surface treatment agent.
• the obtained organic solvent dispersion had a low transmittance.

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